fix(query-builder): Improve the stability of token keys

[malwilley]

Previously, the cursor would jump around when entering a free text portion due to the component remounting because the key changed. This makes some changes to avoid keys changing as much as possible:

• Updates token keys from {type}:{cursor_location} to {type}:{type_index}
• Renames space tokens to free_text since they are treated the same and it keeps the keys stable